Summary: A High-Q Low-Voltage HARPSS Tunable Capacitor
Pejman Monajemi and Farrokh Ayazi
School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
Abstract -- This paper reports on the design, fabrication and
testing of a low-voltage, high-Q one-port tunable capacitor in
single wafer low-resistivity silicon substrate for RF filtering
applications. The tuning range of the parallel plate capacitor is
measured to be 2:1 for a range of 2.5-5pF with a tuning voltage of
only 2V. The electrical quality factor (Q) of a 1mm×1.5mm, 60µm
thick capacitor with a gap of 1µm was measured to be 99 at
400MHz and 49 at 1GHz and the return loss was below 0.5dB.
The self-resonance frequency is above 10GHz.
Index Terms -- Tunable capacitor, HARPSS.
I. INTRODUCTION
MEMS tunable capacitors have small size, high-Q, wide
tuning range, and low insertion-loss, and can replace the
conventional solid-state varactor diodes on integrated passive
and/or active substrates. Various designs of RF
micromechanical tunable capacitors with very high electrical
Q have been reported in the literature [1-4]. These devices